[Library Manager] Add MovingAverage lib

[AlexandreHiroyuki]

Moving Average Library

https://github.com/AlexandreHiroyuki/MovingAverage_ArduinoLibrary

First stable release v1.2.1

• Implements a simple moving average class

The latest stable release v1.3.1

• Added a new feature that allows reading the array through the operator syntax

Example:
MovingAverage<int> a(10, 1); Serial.println(a[2]);

[cmaglie]

Done.